of should be acknowledged to identify future research directions. This work provides some suggested directions for future research. Suggestions include the following: The ego behavior and opinions are not merely determined by exogenous mechanisms (the behavior and opinions of others), but also by endogenous mechanisms (reaction to various other constraints and opportunities granted by the ego conditions). This process is typically modeled in sociology as an autocorrelation model. Owing to the lack of an endogenous mechanism, this study highlights the need for further research on the autocorrelation model of international technology diffusion to simultaneously consider exogenous and endogenous mechanisms. Second, this work explores the social contagion effect at the global level, but does not individually examine the actions of focal countries at the block level (e.g. core, semi-periphery and periphery). Global stratification patterns can be made more specific if researchers focus on the interactions between certain countries and others. Finally, this study focuses on social contagion effects to the exclusion of other social network analysis. A useful direction for future works would be to apply more indicators and conceptions of social network analysis to analyze the data. Acknowledgements
The authors thank Professor Daim and two anonymous referees for their insightful and valuable comments on the paper. Les Davy, Pai-Yu Liu, Cheng-Chi Hsieh, and Ted Knoy are thanked for their professional assistance. Also, this research was supported by a grant from the National Science Council of Taiwan under Contract No. 97-2410-H-260-011-MY3. This support is gratefully acknowledged. References
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